Template synthesis of graphitic hollow carbon nanoballs as supports for SnOx nanoparticles towards enhanced lithium storage performance

Engineering a hierarchical reduced graphene oxide and lignosulfonate derived carbon framework supported tin dioxide nanocomposite for lithium-ion storage

Tin dioxide (SnO2) is widely recognized as a high-performance anode material for lithium-ion batteries. To simultaneously achieve satisfactory electrochemical performances and lower manufacturing costs, engineering nano-sized SnO2 and further immobilizing SnO2 with supportive carbon frameworks via eco-friendly and cost-effective approaches are challenging tasks. In this work, biomass sodium lignosulfonate (LS-Na), stannous chloride (SnCl2) and a small amount of few-layered graphene oxide (GO) are employed as raw materials to engineer a hierarchical carbon framework supported SnO2 nanocomposite. The spontaneous chelation reaction between LS-Na and SnCl2 under mild hydrothermal condition generates the corresponding SnCl2@LS sample with a uniform distribution of Sn2+ in the LS domains, and the SnCl2@LS sample is further dispersed by GO sheets via a redox coprecipitation reaction. After a thermal treatment, the SnCl2@LS@GO sample is converted to the final SnO2/LSC/RGO sample with an improved microstructure. The SnO2/LSC/RGO nanocomposite exhibits excellent lithium-ion storage performances with a high specific capacity of 938.3 mAh/g after 600 cycles at 1000 mA g-1 in half-cells and 517.1 mAh/g after 50 cycles at 200 mA g-1 in full-cells. This work provides a potential strategy of engineering biomass derived high-performance electrode materials for rechargeable batteries.

Ball-Milled Silicon with Amorphous Al2O3/C Hybrid Coating Embedded in Graphene/Graphite Nanosheets with a Boosted Lithium Storage Capability

Electrochemical active silicon has attracted great attention as anodes for lithium-ion batteries owing to a high theoretical capacity of 4200 mA h g^-1. In this work, ball-milled silicon particles with submicron size were strategically modified with a hybrid coating of amorphous alumina and carbon, which simultaneously embedded in a porous framework of in situ exfoliated graphene/graphite nanosheets (GGN). The composite exhibits an enhanced electrochemical performance, including high cycling stability and superior rate capability. An initial discharge capacity of 1294 mA h g^-1 and a reversible charge capacity of 1044 mA h g^-1 at 0.2 A g^-1 can be achieved with a high initial Coulombic efficiency of up to ca. 81%. Additionally, the composite can remain 902 mA h g^-1 after 100 discharge/charge cycles, accounting for a high retention of about 86%. This silicon composite is a promising anode material for high performance lithium-ion batteries with a high energy density, and the facile one-pot fabrication route is low cost and scalable, with a great prospect for practical application.

Stable Rooted Solid Electrolyte Interphase for Lithium-Ion Batteries

Metal oxide-based materials are attractive anode candidates for lithium-ion batteries (LIBs) because of their high theoretical capacity. However, these materials suffer from large volume expansion and poor stability of solid electrolyte interphase (SEI) during the charge-discharge process, casusing rapid capacity degradation. Herein, we report that Li₃PO₄-rooted and intact SEI in situ formed on the phosphate-modified SnO₂/CNFs during cycling. The phosphate anions in the anode, could serve as the root to form Li₃PO₄ by bonding with Li ions and participate in the formation of the SEI, thus firmly anchoring and stabilizing the SEI layer. The rooted Li₃PO₄ and enriched LiF in the SEI could synergistically enhance the Li-ion diffusion, significantly reduce the volume expansion, and lead to ultrastable cycling performance over 1100 charge-discharge cycles at 1 A g^-1. This work provides a new avenue for forming stable SEI rooted into the anode and inspires the development of interface engineering toward electrochemical energy storage.

Nanomaterials Synthesis through Microfluidic Methods: An Updated Overview

Microfluidic devices emerged due to an interdisciplinary "collision" between chemistry, physics, biology, fluid dynamics, microelectronics, and material science. Such devices can act as reaction vessels for many chemical and biological processes, reducing the occupied space, equipment costs, and reaction times while enhancing the quality of the synthesized products. Due to this series of advantages compared to classical synthesis methods, microfluidic technology managed to gather considerable scientific interest towards nanomaterials production. Thus, a new era of possibilities regarding the design and development of numerous applications within the pharmaceutical and medical fields has emerged. In this context, the present review provides a thorough comparison between conventional methods and microfluidic approaches for nanomaterials synthesis, presenting the most recent research advancements within the field.

Formation of monomeric Sn(ii) and Sn(iv) perfluoropinacolate complexes and their characterization by 119Sn Mössbauer and 119Sn NMR spectroscopies

The synthesis and characterization of a series of Sn(ii) and Sn(iv) complexes supported by the highly electron-withdrawing dianionic perfluoropinacolate (pin^F) ligand are reported herein. Three analogs of [Sn^IV(pin^F)₃]^2- with NEt₃H⁺ (1), K⁺ (2), and {K(18C6)}⁺ (3) counter cations and two analogs of [Sn^II(pin^F)₂]^2- with K⁺ (4) and {K(15C5)₂}⁺ (5) counter cations were prepared and characterized by standard analytical methods, single-crystal X-ray diffraction, and ¹¹⁹Sn Mössbauer and NMR spectroscopies. The six-coordinate Sn^IV(pin^F) complexes display ¹¹⁹Sn NMR resonances and ¹¹⁹Sn Mössbauer spectra similar to SnO₂ (cassiterite). In contrast, the four-coordinate Sn^II(pin^F) complexes, featuring a stereochemically-active lone pair, possess low ¹¹⁹Sn NMR chemical shifts and relatively high quadrupolar splitting. Furthermore, the Sn(ii) complexes are unreactive towards both Lewis bases (pyridine, NEt₃) and acids (BX₃, Et₃NH⁺). Calculations confirm that the Sn(ii) lone pair is localized within the 5s orbital and reveal that the Sn 5p_x LUMO is energetically inaccessible, which effectively abates reactivity.

Graphitic Nanocup Architectures for Advanced Nanotechnology Applications

The synthesis of controllable hollow graphitic architectures can engender revolutionary changes in nanotechnology. Here, we present the synthesis, processing, and possible applications of low aspect ratio hollow graphitic nanoscale architectures that can be precisely engineered into morphologies of (1) continuous carbon nanocups, (2) branched carbon nanocups, and (3) carbon nanotubes-carbon nanocups hybrid films. These complex graphitic nanocup-architectures could be fabricated by using a highly designed short anodized alumina oxide nanochannels, followed by a thermal chemical vapor deposition of carbon. The highly porous film of nanocups is mechanically flexible, highly conductive, and optically transparent, making the film attractive for various applications such as multifunctional and high-performance electrodes for energy storage devices, nanoscale containers for nanogram quantities of materials, and nanometrology.

The Sn–C bond at the interface of a Sn2Nb2O7–Super P nanocomposite for enhanced electrochemical performance

A Sn₂Nb₂O₇–Super P nanocomposite (SNO–SP) as an anode material for lithium ion batteries is successfully synthesized through a simple hydrothermal method.

Hollow nanoparticle-assembled hierarchical NiCo2O4 nanofibers with enhanced electrochemical performance for lithium-ion batteries

Hollow NiCo₂O₄ nanoparticle-assembled electrospun nanofibers showed tailorable electrochemical activity and tunable lithium storage properties.

Porous N-doped carbon nanoflakes supported hybridized SnO2/Co3O4 nanocomposites as high-performance anode for lithium-ion batteries

Alloy-/conversion-type metal oxides usually exhibit high theoretical lithium storage capacities but suffer from the large volume change induced electrode pulverization and the poor electric conductivity, which limit their practical applications. Hybrid/mixed metal oxides with different working mechanisms/potentials can display advantageous synergistic enhancement effect if delicate structure engineering is performed. Herein, atomically hybridized SnO₂/Co₃O₄ nanocomposites with amorphous nature are successfully cast onto the porous N-doped carbon (denoted as NC) nanoflakes through facile pyrolysis of the tin (II) 2-ethylhexanoate (C₁₆H₃₀O₄Sn) and cobalt (II) 2-ethylhexanoate (C₁₆H₃₀O₄Co) mixture within NC nanoflakes in air at 300 °C for 1 h. The Sn/Co atomic ratio and the loading amount of SnO₂/Co₃O₄ can be readily controlled, whose effect on lithium storage are investigated as anodes for lithium ion batteries (LIBs). Notably, SnO₂/Co₃O₄@NC (R_Sn/Co = 1.25) nanoflakes exhibit the most excellent lithium storage properties, delivering a reversible capacity of 1450.3 mA h g^-1 after 300 cycles at 200 mA g^-1, which is much higher than that of the single metal oxide SnO₂@NC and Co₃O₄@NC electrodes.

Casting amorphorized SnO2/MoO3 hybrid into foam-like carbon nanoflakes towards high-performance pseudocapacitive lithium storage

We report an amorphorization-hybridization strategy to enhance lithium storage by casting atomically mixed amorphorized SnO₂/MoO₃ into porous foam-like carbon nanoflakes (denote as SnO₂/MoO₃@CNFs, or SMC in short), which are simply prepared by annealing tin(II)/molybdenum(IV) 2-ethylhexanoate within CNFs under ambient atmosphere at a low temperature (300 °C). The SnO₂/MoO₃ loading amount within CNFs can be easily adjusted by controlling the Sn/Mo/C precursors. When examined as lithium ion battery (LIB) anode materials, the amorphorized SnO₂/MoO₃@CNFs with carbon content of 32 wt% (also denote as SMC-32, in which the number represents the carbon content) deliver a high reversible capacity of 1120.5 mA h/g after 200 cycles at 200 mA/g and then 651.5 mA h/g after another 300 cycles at 2000 mA/g, which is much better than that of the crystalline SnO₂/CNFs (carbon content of 34 wt%), MoO₃/CNFs (carbon content of 22.7 wt%), or SnO₂/MoO₃@CNFs (with lower carbon contents of 11 and 25 wt%). The electrochemical measurements as well as the ex situ structure characterization clearly suggest that combination of amorphorization and hybridization of SnO₂/MoO₃ with CNFs synergistically contributes to the superior lithium storage performance with high pseudocapacitive contribution.

Mesoporous NH4NiPO4·H2O for High-Performance Flexible All-Solid-State Asymmetric Supercapacitors

Nowadays, wearable energy storage devices have been growing rapidly, but flexible systems with both excellent cycling stability and decent flexibility are still challenging. In this work, a flexible all-solid-state NH₄NiPO₄·H₂O//graphene supercapacitor with remarkable performance was successfully assembled. When cycled at a current density of 5 mA cm⁻², the device delivered 121 mF cm⁻², and showed good cycling stability after 3,000 cycles. Moreover, the all-solid-state NH₄NiPO₄·H₂O//graphene supercapacitor also exhibit high mechanical flexibility with well-maintained specific capacitance, even under bending to arbitrary angles (up to 180°) and different weights (up to 50 g).

Electronic Peculiarities of a Self-Assembled M12L24 Nanoball (M = Pd+2, Cr, or Mo)

We use molecular mechanics and DFT calculations to analyze the particular electronic behavior of a giant nanoball. This nanoball is a self-assembled M₁₂L₂₄ nanoball; with M equal to Pd⁺²; Cr; and Mo. These systems present an extraordinarily large cavity; similar to biological giant hollow structures. Consequently, it is possible to use these nanoballs to trap smaller species that may also become activated. Molecular orbitals, molecular hardness, and Molecular Electrostatic Potential enable us to define their potential chemical properties. Their hardness conveys that the Mo system is less reactive than the Cr system. Eigenvalues indicate that electron transfer from the system with Cr to other molecules is more favorable than from the system with Mo. Molecular Electrostatic Potential can be either positive or negative. This means that good electron donor molecules have a high possibility of reacting with positive regions of the nanoball. Each of these nanoballs can trap 12 molecules, such as CO. The nanoball that we are studying has large pores and presents electronic properties that make it an apposite target of study.

Chemical vapor deposition growth of carbon nanotube confined nickel sulfides from porous electrospun carbon nanofibers and their superior lithium storage properties

Multidimensional architecture design is a promising strategy to explore unique physicochemical characteristics by synergistically integrating different structural and compositional materials. Herein, we report the facile synthesis of a novel dendritic hybrid architecture, where carbon nanotubes (CNTs) with nickel sulfide nanoparticles encapsulated inside are epitaxially grown out of the porous electrospun N-doped carbon nanofibers (CNFs) (denoted as CNT@NS@CNFs) through a combined strategy of electrospinning and chemical vapor deposition (CVD). The adopted thiophene (C₄H₄S) not only serves as a carbon source for the growth of CNTs but also as a sulfur source for the sulfurization of Ni particles and S-doping into carbon matrices. When examined as an anode material for lithium-ion batteries (LIBs), the dendritic CNT@NS@CNFs display superior lithium storage properties including good cycle stability and high rate capability, delivering a high reversible capacity of 630 mA h g^-1 at 100 mA g^-1 after 200 cycles and 277 mA h g^-1 at a high rate of 1000 mA g^-1. These outstanding electrochemical properties can be attributed to the novel hybrid architecture, in which the encapsulation of nickel sulfide nanoparticles within the CNT/CNFs not only efficiently buffers the volume changes upon lithiation/delithiation, but also facilitates charge transfer and electrolyte diffusion owing to the highly conductive networks with open frame structures.

Integrating TiO₂/SiO₂ into Electrospun Carbon Nanofibers towards Superior Lithium Storage Performance

In order to overcome the poor electrical conductivity of titania (TiO₂) and silica (SiO₂) anode materials for lithium ion batteries (LIBs), we herein report a facile preparation of integrated titania⁻silica⁻carbon (TSC) nanofibers via electrospinning and subsequent heat-treatment. Both titania and silica are successfully embedded into the conductive N-doped carbon nanofibers, and they synergistically reinforce the overall strength of the TSC nanofibers after annealing (Note that titania⁻carbon or silica⁻carbon nanofibers cannot be obtained under the same condition). When applied as an anode for LIBs, the TSC nanofiber electrode shows superior cycle stability (502 mAh/g at 100 mA/g after 300 cycles) and high rate capability (572, 518, 421, 334, and 232 mAh/g each after 10 cycles at 100, 200, 500, 1000 and 2000 mA/g, respectively). Our results demonstrate that integration of titania/silica into N-doped carbon nanofibers greatly enhances the electrode conductivity and the overall structural stability of the TSC nanofibers upon repeated lithiation/delithiation cycling.

Synthesis of double-shelled SnO2 hollow cubes for superior isopropanol sensing performance

Multi-shelled hollow structures have attracted extensive attention due to their promising performance in many areas.